The standard doesn’t specify this, though I recall us discussing this and IIRC agreeing that ndims equal to zero was well-defined and not an error. And there is nothing in the standard that suggests that it should be an error, just nothing that says it shouldn’t. Bill William Gropp Acting Director and Chief Scientist, NCSA Director, Parallel Computing Institute Thomas M. Siebel Chair in Computer Science University of Illinois Urbana-Champaign On Nov 8, 2016, at 11:40 PM, Gilles Gouaillardet <[email protected]> wrote:
Folks,
Does the standard specifiy the behavior of MPI_Dims_create() when the ndims argument is zero ?
the standard only says negative input values of dims[i] are erroneous, but does not say anything about ndims.
ndims is the number of Cartesian dimensions (integer), and though a negative number likely looks erroneous
to most of us, a zero value is incorrect from a mathematical point of view (and i wish i remembered that ...)
Could someone tell me how a zero value should be interpreted ?
(e.g. valid/invalid/up to the implementor ?)
FWIW, currently
in MPICH, this is a no-op.
In Open MPI, this is an error by default, but if parameter check is manually disabled, then this is a no-op too.
Cheers,
Gilles
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